1. Field of the Invention
This invention relates generally to reciprocating wipers, e.g., windshield wipers, and, specifically, to windshield wipers having one or more blades which have formations therein which permit flow of liquid, e.g., water, through the blades in one direction of movement of the wiper, but not in the other.
2. Related Art
Known wipers usually comprise one or more resilient rubber blades mounted on an arm which reciprocatingly sweeps the blades sideways across the surface of a window, vehicle windshield, headlight lens or other formation. As the blades move across the surface, they push water or other liquids on the surface sideways until the arm reaches the limit of its travel, discharging an accumulation of water at the point where the arm stops and reverses its motion. The result is a fan-shaped cleared arc on the surface which is swept clear of water, at least temporarily. In a typical windshield arrangement, an adjacent wiper assembly pushes some or all of the water it has cleared into the cleared arc of the adjacent wiper assembly. The accumulated water reduces visibility through a windshield or the like and presents a driving hazard. Removal of the water from the windshield is accomplished only when the accumulated water runs off the bottom and sides of the windshield or, in moving vehicles, is pushed off the upper edge of the windshield by aerodynamic pressure.
It is well known in the art to provide two or more parallel wiper blades on a single wiper arm to increase the efficiency of the wiping action, as shown by the following patents.
U.S. Pat. No. 5,168,595, issued to James L. Naylor, Jr. on Dec. 8, 1992 and entitled xe2x80x9cWindshield Wiper Blade and Assemblyxe2x80x9d, discloses one such system. A single wiper arm assembly 20 (shown in FIGS. 1 through 7) has an elongated blade carrier assembly 36 pivotally mounted to the arm 24, and first and second blades 26 and 27 mounted on the blade assembly 36.
U.S. Pat. No. 4,745,653, issued to Bedrich V. Bliznak on May 24, 1988 and entitled xe2x80x9cWiper/Scraper/Washer Blade for Windows on Transportation Meansxe2x80x9d, discloses a multiple edged blade 1 (shown in FIG. 1) having two blades of different cross sections in contact with the surface to be cleaned, the smooth blades having a serrated appearance in cross-sectional view.
U.S. Pat. No. 4,567,621, issued to Robert L. Alley, Jr. on Feb. 4, 1986 and entitled xe2x80x9cComposite Windshield Wiper Assemblyxe2x80x9d, discloses a wiper blade assembly A (shown in FIG. 1) having a pair of spaced wiper blade elements 42, 44 having thin resilient wiping edges 42a, 44a. A scrubbing block 50 occupies the entire space between the wiping blade elements and protrudes at 52 past the wiping edges 42a, 44a. 
U.S. Pat. No. 4,339,839, issued to Robert E. Knights on Jul. 20, 1982 and entitled xe2x80x9cWindscreen Wipersxe2x80x9d, discloses (see FIG. 1) a windscreen wiper having a pair of spaced parallel wiping lips 22 bounding a space 28 in which is a bristle 32.
U.S. Pat. No. 3,916,473, issued to Zelmer L. Williams on Nov. 4, 1975 and entitled xe2x80x9cWiper for Windshieldsxe2x80x9d, discloses (see FIG. 6) a single longitudinal blade 38 provided with a longitudinal groove 40 running substantially the length of the blade 38. An aperture 42 in the blade base 36 permits feed of a fluid, such as windshield washer fluid to the groove 40, from whence it flows to the windshield via passages 72 which run from the base of the blade 36 to the windshield.
U.S. Pat. No. 1,441,593, issued to Harry L. Lavietes on Jan. 9, 1923 and entitled xe2x80x9cWindshield Cleanerxe2x80x9d, discloses a windshield wiper (see FIG. 1) having multiple strips 16 held in a pair of longitudinal grooves 15.
U.S. Pat. No. 1,370,910, issued to Julius Pederson on Mar. 8, 1921 and entitled xe2x80x9cWindshield Cleanerxe2x80x9d, discloses in FIG. 1a windshield cleaner having wiper strips 11 held in channels 16 of wiper bar 10.
The present invention provides a wiper for wiping liquid from a surface. The wiper comprises a first blade having therein a plurality of formations disposed along at least a portion of the length thereof. The formations are configured: (a) to permit the passage of liquid through the first blade when the first blade moves across such surface in a first direction, and (b) to inhibit passage of liquid through the first blade when the first blade moves across such surface in a second direction opposite to the first direction.
In one aspect of the invention, the first blade is flexible and the formations therein are opened to permit the passage of water therethrough by flexing of the first blade during its movement in the first direction and are closed to inhibit the passage of water therethrough by flexing of the first blade during its movement in the second direction.
In another aspect of the present invention, the first blade has first and second opposite sides joined by a wiping face, the first side and the wiping face intersecting to define a first edge, and the second side and the wiping face intersecting to define a second edge.
In one aspect of the invention the wiper has a low friction material disposed on the first side of the blade at the first edge thereof whereby the coefficient of friction of the first side of the blade is lower than that of the second side of the blade. In other aspects of the invention, the formations comprise notches in, and/or protrusions on, the first edge, and/or slits extending through the first blade to define flap members between adjacent slits.
In the latter aspect of the invention, the slits may converge towards each other to provide a plurality of wedge-shaped flap members.
Yet another aspect of the present invention provides for the wiper to further comprise a second blade disposed substantially parallel to the first blade, the first and second blades defining a channel therebetween. In this aspect of the present invention, the second blade may have therein a plurality of formations disposed along at least a portion of the length thereof, which formations are configured (a) to permit the passage of liquid into the channel through the second blade when the second blade moves across such surface in the second direction and (b) to prevent the passage of liquid through the second blade when the second blade moves across the surface in the first direction. In this aspect of the present invention, the second blade may be flexible and the formations therein are dimensioned and configured to be opened by flexing of the second blade during its movement in the second direction and closed by flexing of the second blade during movement of the second blade in the first direction.
Other aspects of the invention provide for a wiper which further comprises at least one intermediate blade disposed between the first and second blades. For example, the wiper may comprise one intermediate blade which divides the channel longitudinally into first and second courses. In this aspect of the present invention, the intermediate blade may be dimensioned and configured to prevent the passage of liquid therethrough, whereby liquid which passes through he first blade is constrained to flow along the first course and liquid which passes through the second blade is constrained to flow along the second course.
In a particular embodiment of the present invention, the wiper is comprised of a first lade and a second blade disposed substantially parallel to each other to define a channel therebetween. Each blade is flexible and has therein a plurality of formations disposed along at least a portion of the length thereof. The formations are configured to attain the following results. The passage of liquid through the first blade is permitted and the passage of liquid through the second blade is inhibited when the wiper moves across such surface in a first direction, by the formations in the first blade being opened and those in the second blade being closed by flexing of the blades during such movement in the first direction. Similarly, the passage of liquid through the first blade is inhibited and the passage of liquid through the second blade is permitted when the wiper moves across such surface in a second direction opposite to the first direction, by the formations in the second blade being closed and those in the first blade being opened by flexing of the blades during such movement in the second direction.
Yet another aspect of the present invention provides a wiper for wiping liquid from a surface and comprising a first blade having first and second sides and a plurality of passages therethrough from the first side to the second side and a second blade arranged substantially parallel to the first blade and defining a channel between the blades.
Still another aspect of the present invention provides a wiper for wiping liquid from a surface, the wiper comprising first and second substantially parallel blades, each blade having respective first and second opposite sides joined by a respective wiping face, each first side intersecting its wiping face to define an exterior edge and each second side intersecting its wiping face to define an interior edge. The wiper of this aspect of the invention has low friction material, e.g., polytetrafluoroethylene, disposed upon the first side of the first blade at the first edge thereof and on the first side of the second blade at the first edge thereof. In this way, the coefficient of friction of the first side of the first blade is lower than that of the second side of the first blade, and the coefficient of friction of the first side of the second blade is lower than that of the second side of the second blade.
Yet another aspect of this invention relates to an improvement in a wiper for wiping a liquid from a surface, the wiper comprising at least a primary liquid-diverting edge and a lateral liquid-diverting edge, the improvement comprising that the lateral liquid-diverting edge has at least one notch formed thereon to permit the flow of liquid therethrough. Optionally, such a wiper may have a plurality of notched lateral edges and a channel between the lateral edges.
This invention also provides an improvement in a windshield wiper assembly or a bridge arm assembly comprising two substantially parallel wipers each comprising a wiper blade, the blades defining a channel between them. The improvement comprises that one of the wipers comprises formations to permit water to pass through the blade. Optionally, there may be a guard strip extending from one wiper to the other in the region of the formations.
A method aspect of the present invention provides a method of wiping liquid from a surface utilizing a wiper comprising first and second blades substantially as described above. The method comprises the steps of moving the wiper in the first direction over a surface containing water to flow the liquid through the first blade and into the channel, moving the wiper in the second direction and flowing the liquid out of the at least one open end of the channel.
The method aspect of the invention includes cyclically moving the wiper alternately in the first and second directions.
A particular method aspect of the present invention includes flowing liquid out of the at least one open end of the channel during movement in both the first and second directions.
In another method aspect of the present invention there is utilized a wiper which further comprises an intermediate blade which is disposed between, spaced from, and parallel to the first and second blades and divides the channel longitudinally into first and second substantially parallel courses, the intermediate blade being dimensioned and configured to prevent the passage of liquid therethrough. This aspect of the method includes flowing liquid which passes through the first blade through the first course, and flowing liquid which passes through the second blade through the second course.
As used herein and in the claims, reference to permitting xe2x80x9cthe passage of liquid throughxe2x80x9d a blade or xe2x80x9cthe flow of liquid throughxe2x80x9d a blade, or words of like import, means that as the blade is moved across a liquid-containing surface with the wiping face of the blade in contact with the surface, at least some of the liquid contacted by the blade is able to remain on the surface despite passage of the blade thereover. This xe2x80x9cpassing-overxe2x80x9d or xe2x80x9cpassing through (the blade)xe2x80x9d action is the result of formations on the blade. In some embodiments the formations themselves provide clearance for the liquid relative to the passing blade, whereas in other embodiments the formations raise portions of the wiping face of the blade from the surface to provide clearance for the surface liquid under the raised portions of the moving blade. On portions of the blade lacking such formations, the blade inhibits or, preferably, prevents the passing through of liquid and can therefore wipe liquid from the surface. As used herein and in the claims, the term xe2x80x9cinhibitxe2x80x9d is meant to encompass the concept of preventing, and thus means preventing in whole or in part.